Well, here it is - entitled "The House of Data". I figured that, since Data was an extremely rare individual, he might have started his own family crest. I based the overall design on those family crest printouts you can order at places like Colonial Williamsburg or EPCOT Center:
Symbolism meaning:
Funny thing is, Data was never actually my favorite character on the show, but it made sense to me that he would have made his own coat of arms as a part of his own self-discovery and self-awareness, analyzing the most important and significant aspects of his life, whether enjoyable (playing the violin, time in Starfleet, Spot, etc.) or not so much (Lore, the Dominion War/fighting with the Borg in First Contact, learning the true nature of B-4, etc.) - all things that made him who he was on his journey to know what it was to be human.
Enjoy!

Symbolism meaning:
- The gold color is taken from a pixel capture of his uniform and the lighter beige color is taken from a pixel capture of his skin.
- The first panel shows a violin and a First Contact-style phaser rifle, the former representing his devotion as an artist and the latter representing his skills as a combat veteran. The rifle is pointing down, signifying that he will only engage in combat in self-defense.
- The second panel shows his Starfleet insignia and rank, for obvious reasons.
- The third panel shows three hands, representing Data and his two brothers, Lore and B-4.
- The fourth panel shows Data's beloved cat, Spot, with a traditional heraldic flair. I would have added cat paw prints denoting Spot's kittens from the TNG episode "Genesis", but I could never get a good answer anywhere as to how many she actually had. Not a big deal. Spot was more important to Data.
- The whole motif is topped-off with Data's emotion chip over the helmet ("Generations" version). I wanted to use the original version of the chip from "Brothers", but I couldn't get a clear picture of it, as it's not available in HD yet and it always seemed to be out of focus in these tiny tweezers being held by Soong. So, I used the bigger one from the movie.
Funny thing is, Data was never actually my favorite character on the show, but it made sense to me that he would have made his own coat of arms as a part of his own self-discovery and self-awareness, analyzing the most important and significant aspects of his life, whether enjoyable (playing the violin, time in Starfleet, Spot, etc.) or not so much (Lore, the Dominion War/fighting with the Borg in First Contact, learning the true nature of B-4, etc.) - all things that made him who he was on his journey to know what it was to be human.
Enjoy!